What it is and what it does
The Siemens 3RK1300-1AS01-0AA3 is an EM 300 DS electromechanical direct starter designed for the ET 200X distributed I/O system. It combines motor starting, bimetal overload protection, and PROFIBUS DP communication in a single IP65-rated enclosure, so it can be mounted directly on the machine frame rather than in a central cabinet. Rated for AC-3 duty at 400 V, it switches a 0.55 kW motor load and has an adjustable full-scale current range of 1.1 to 1.6 A. The 50 A short-circuit breaking capacity (Icu) at 400 V means it can safely interrupt a fault up to that level without requiring an upstream fuse or breaker to clear first — useful for selectivity in a distributed motor branch.
Fieldbus and brake integration
The starter includes a built-in PROFIBUS DP interface for direct connection to the control network, eliminating the need for a separate gateway module. It also has a motor brake output for internally supplied brakes — a common requirement on vertical-axis or high-inertia conveyor drives where the load must hold position when power is removed. The DC voltage type and tab terminals for the main current circuit are typical for this class of distributed starter; the 9-pole motor feeder and 9-pole power connection mate with the ET 200X system cabling.
Environmental and mounting
IP65 protection means the enclosure is dust-tight and protected against low-pressure water jets — suitable for washdown areas or outdoor installation without an additional cabinet. The operating temperature range of 0 to 55 °C covers most industrial floor conditions, though it should be derated if mounted near a heat source. Physical footprint is 140 mm wide, 270 mm high, and 134 mm deep — sized to fit the ET 200X mounting rail. The equipment marking per DIN EN 61346-2 (Q) identifies it as a motor starter in the schematic.